The present invention relates generally to orthopaedic fixation devices, and in particular to a fixation system for bones having an intramedullary canal.
Various types of intramedullary nails are already known in the state of the art, which are expandable in a limited section of the nail in order to allow the fixation of the nail against the bone cortex, e.g. by means of radially deploying a number of blades in the distal portion of the intramedullary nail. These devices, however, when in use may lead to clinical results that are not optimally consistent with the state of the art concept of fracture treatment. For instance, an intramedullary nail which is not extrafocal may negatively affect endosteal vascularisation in the fracture area because the largest expansion of the nail is in the fracture area. Also, the largest expansion of the nail in the fracture area may generate forces which may have the tendency to separate fragments in comminuted fractures or, in the case of longitudinal non-dislocated fractures to increase the gap and to dislocate fragments which may lead to loosening of the fixation. Thus, despite these developments, a need exists for a nail having expandable parts which may be located extrafocally, leaving the fracture area less affected from radial forces. Such a nail might be particularly strong in the middle partxe2x80x94between the proximal and distal sectionsxe2x80x94of the nail and might not require the use of fluoroscopy for distal nor proximal locking.
The invention in one embodiment is related to an intramedullary nail having a head, a tip, and a longitudinal axis for fixation of a fractured bone having a medullary canal. The intramedullary nail may comprise a hollow cylindrical sleeve extending along the longitudinal axis and surrounding a locking element coaxially to the longitudinal axis. The nail may further include a first radially expandable section adjacent to the head, a second radially expandable section adjacent to the tip, and a non-expandable section disposed between the first and second radially expandable sections. The head of the intramedullary nail may be provided with a distraction mechanism, by means of which the first and second radially expandable sections are distractible transverse to said longitudinal axis. The non-expandable section may comprise at least one unslotted tubular piece. In one embodiment of the intramedullary nail the non-expandable section has a length in the range of 10 to 25 mm. In another embodiment, the non-expandable section of the intramedullary nail has a length in the range of about 15 mm to about 22 mm.